HYDROLOGICAL SOIL MAPPING LOWER AUSTRIA AN APPROACH FOR HYDROLOGICAL SOIL CLASSIFICATION AND RUNOFF ASSESSMENT

Besides rainfall characteristics, the generation of storm runoff is mainly influenced by the spatial distribution of landscape forming parameters. Geomorphology, vegetation, land use, soil and geology determine the processes of runoff generation. Especially soil properties like pore volume, storage capacity and (saturated) hydraulic conductivity may accelerate or decrease the amounts of surface or interflow runoff. Most common assessment approaches and hydrological models use both soil and land use / land cover information. Different concepts were developed for this purpose e.g. the Curve Number procedure (US Department of Agriculture, 1972) or the HOST method (Boorman et al., 1995). To delimit areas with accelerated response to rainfall, decision schemes indicating the dominant runoff process were developed (Peschke et al., 1999; Schmocker-Fackel et al., 2007). The study area comprises the whole of Lower Austria with a surrounding 1-km buffer, covering a total area of about 20.400 km2. To obtain information about the hydrological response of soils to rainfall events, a stepwise procedure with the final result of site specific hydrological soil and response types was developed, based on established concepts, but also including new schemes.